1, Since user has changed the computer name, need change it back.
2, first , user MUST know the password of local administrator, if not, this VM can't be login.
3, quit from the domain: login VM from OMS with local administrator, right click"computer --properties--advanced system settings--computer name--workgroup"
4, input "WORKGROUP" and click OK. then restart to take effect.
5, change the computer name back and then restart
6, join domain, the method is the same as "quit from domain"